Hydroponics 101: How Hydroponics Works

A vast number of people have heard the term hydroponics; they may even know it’s growing plants without soil and in water. However, there is much more to it than shoving seedlings in water. If you were to do this, they would grow for a very short period, and then keel over and die.

The theory and practice in hydroponics is more in depth, and for new growers it can be overwhelming. We will look at the history of hydroponics, how it now works from its early beginnings, and then we will go through each part, and see how each works together, and influence each other.

The History of Hydroponics

The term hydroponics originates from “Hydro” which means water, and “Ponos” which means labor. It may sound like a modern technique, but in fact, it stems all the way back to “The Hanging Gardens of Babylon,” and the “Floating Gardens of China.”

Thousands of years ago, our ancestors were using the same techniques. While the principles are the same, the most significant differences are in systems construction materials, and how we now source nutrients.

It was in the past 100 years where there was a reference to the more up-to-date methods of hydroponics.

In the University of California, Berkeley, there was a man by the name of William Frederick Gericke. He began popularizing his ideas that we can grow plants without soil, and instead, they can use a nutrient rich solution.

At this time, it was unheard of, and his peers were quick to doubt and discard his claims. However, he was to prove all his critics wrong when he grew some very large tomato vines using his methods.

There was more research, they saw benefits for cultivation without soil, and Gericke came to coin the term, as we know it now, “Hydroponics.”

Hydroponic Benefits

Most growers know plants will grow faster and larger in hydroponics systems than in soil. There are however reasons they are able to do this. Here are the top four benefits of hydroponics over soil.

1# Pests and Infections

A hydroponic system will be away from any external influences. It will be a closed, water-driven system. Once this happens, there are no soil-borne pests around to hamper the growth of plants; likewise, the same applies to fungal infections and diseases, which can come from soil growth.

Soil growing is an ecosystem for all manner of microbes, insects, fungi and bacteria. There is a food chain occurring, and when you add plants into the equation, there are only two options. They can become a home for pests or fungi, or they can become a part of the food chain.

2# Chemical Usage

When growing in soil, there is a likelihood that herbicides, pesticides and all manner of chemicals are used to control animal and plant pests. Once you have a hydroponic system, you can eradicate the need for these. If soil growing is on a large scale, the grower or farmer’s health can suffer, in hydroponics, they won’t be under the same risk.

Natural means or fine screens such as mosquito nets can tend to most pests you may find in hydroponics. The only time you will be adding chemicals into the mix is when you are adding your nutrients.

One final area of benefit under chemicals is the reduced time you have for weeding. Because the growing area is segregated, there is no way for weeds to take hold and grow. This saves time and is one reason why there is no requirement for harmful herbicides.

3# No End of Growing Season

Soil needs time to recover once the harvest is over. In some instances, you can plant a second crop, but once that has come to harvest; you will be at the wrong time of year. This is where growers need to wait until the following spring before starting again.

Hydroponics on the other hand has no season end and has a quick turnaround once all your plants come to harvest. All you need to do is clean and sterilize your system, and re-fill with the next nutrient solution.

All through growing, you can test your nutrient solution and tailor everything to your plants.

4# Faster Growth

Faster growth is the benefit most growers know about. The reason for this is a culmination of the first three advantages. Because there are fewer pests and things your plants need to contend with, your tailoring of nutrients to deliver the optimum levels, makes sure your plants have the ideal growing conditions.

If you were to grow in soil, it takes more preparation to achieve optimum nutrient levels, because soil rarely has ideal growing conditions on its own.

How Hydroponic Systems Work

To understand how hydroponics works, it is good to know the fundamentals of each kind of system, and the benefits they bring. Here are six of the more common varieties of hydroponic system.

Flood and Drain (Ebb & Flow)

Plants sit inside growing pots full of growing medium, or they can sit in large Rockwool growing cubes. Spacing them apart, they then sit inside a flood tray. A timer runs your water pump at intervals to flood the tray to a set level. After a set period, the timer cuts off and your solution runs back into the tank.

Advantages of this system are its simplicity of build and maintenance. This actually mimics natural weather patterns with rain, but on a more frequent basis. As the tray is flooded, plants take up nutrients as they need them, and once the solution drains back, the roots gain oxygen from the atmosphere.

DWC (Deep Water Culture)

Growers suspend their plants above nutrient solutions in this type of system. This can be the lid of your tank, or it can be in a floating raft. To prevent your plants drowning, you use an air pump and air stone to oxygenate the solution.

If you have a raft system, there is less need for you to top the tank with fresh water, because the raft will lower along with the water reduction. If you use the lid of your tank, you do need to make sure water levels are high enough to reach your root systems.

Benefits of these systems are they are cheap to build, easy to run and maintain. Plants never go without water or nutrients. You can also use fewer nutrients in these systems than many others.

Bubbleponics

This is almost identical to a DWC system, albeit a little more advanced. In top-fed DWC systems, the water still reaches your plant roots, and you make use of an air pump and air stone. The difference being you now use a water pump, to deliver your solution via small tubes to the top of your plants root system. This runs back through the growing medium before passing back to the tank.

Benefits are the same as a deep-water culture system, and they receive highly oxygenated water to prevent drowning.

NFT (Nutrient Film Technique)

This system uses a water pump and gravity as the water delivery system. Your plants will sit in pots that sit inside sealed gutters or PVC tubes. These will be on a slight incline, and a continuous flow of nutrients runs along the channels where gravity pulls them back to the lowest point, which will be your tank.

The nutrients circulate, where just the root tips sit in the solution. Oxygen is absorbed by the upper parts of the plants root mass.

Benefits found in this system are plants will receive the ideal blend of nutrients, water and oxygen at all times. Once in operation, these levels are easier to maintain than in most other systems.

Drip Systems

Plants will feed from the continual stream from small tubes. These take water from the tank via a water pump. The amount of water is restricted to the amount that keeps your growing medium moist. All excess water passes back to the tank to recirculate.

Advantages of drip systems are the amount of water you can deliver. This makes it flexible for growing different plants in one system. You may have light feeders with a heavier feeding plant; however, you will need to monitor your nutrient levels carefully.

Aeroponics

This system differs from all the others. Pumps spray a mist of oxygenated water and nutrients against rooting systems. Roots have lots of exposure to the air, so, they can absorb larger amounts of oxygen.

Advantages Aeroponics systems are the faster growing that you can achieve, as well as using less water in your system.

There are a couple of other hydroponic systems, which are variations of the above. There are also the passive versions, which run without using any mechanical methods of water delivery.

How Hydroponic Growing Media Works

There are a few different growing mediums, which are better suited to some hydroponic systems than others. However, in essence, the basic duty of all of them is to give support to your plants.

The second function is for them to hold water and oxygen. We know that roots require plenty of oxygen, and they can only absorb nutrients once they are in contact with water.

Because each growing medium differs, it can make the difference when choosing the correct one for your system. Early systems used sand as their growing medium, and while it offers a solid footing for plants, it lacks being able to deliver oxygen and water efficiently. The biggest problem being the size of the particles.

If you look at the opposite end and use gravel, this delivers plenty of oxygen, but it can’t retain water because this falls straight through the large gaps.

With this, here are the main four types of growing medium you will find.

Perlite

The type you use will be horticultural grade perlite. It is one of the oldest growing mediums in use. Its benefits are it is readily available; it is light and delivers many benefits for any kind of gardening along with hydroponics.

Perlite comes with several benefits, which makes it an ideal growing medium:

Perlite absorbs water, oxygen and nutrients. It hangs onto these until they are ready for use by your plants. This makes it root friendly. Perlite is often an addition to soil because of its benefits, and even in hydroponics, you can mix it with coco coir to increase the water and air holding capacity.

Because perlite is light, it isn’t an ideal medium for flood and drain systems, it can be dislodged and end up flowing down return pipes to your tank. It is however a sterile material, and because of this, it tolerates changes in your nutrient mixes.

Perlite is capable of resisting fungi, which is perfect for a closed system like hydroponics. Anything, which can prevent fungi growth, is a good thing. In the right system, most crop varieties will benefit from perlite use.

Coco Coir

What was once a waste byproduct of the coconut industry turns out to be one of the best growing mediums you can find. Even after coconut harvesting and processing, it delivers natural plant hormones, and is another medium, which resists fungi.

The structure of coir is perfect for fine root hairs to spread and seek out their nutrient source. The coconut fibers are resistant to sun exposure, which they prove by bobbing across the ocean too far-off islands.

Now, with the benefits found for hydroponics, they compress the coir into briquettes. These require soaking before using for the first time. It may take a gallon of water as a minimum for one brick. Once you soak them, they will expand up to six times their original size. This shows coir is an ideal medium because it retains lots of water and oxygen.

Molded Sponges

These sponges are one of the better (miracle) mediums for use in hydroponics. They are a combination of polymer and compost. In most cases, growers use them in the germination stage where they help reduce transplant shock. They hold the ideal amount of air and water while guiding new roots down toward the moisture source.

This feature of molded sponges mimics the way roots seek out nutrients in soil. Using them, helps eliminate one of the bigger problems hydroponics growers face, and that is root systems, which grow in all directions.

Hydroton (Expanded Clay Pebbles)

These expanded clay pebbles are very popular because of their neutral pH. While they only possess moderate air and water retention properties, they are denser and heavier than perlite, so they are ideal in systems where this medium isn’t suitable, notably flood and drain.

These small clay pebbles are fit for re-use in different growing seasons and makes planting and harvesting far easier. Roots have little to cling so, so when you pull up your plants, the majority of the growing medium remains in your pots.

One of the biggest downsides is the possibility of these floating into your tank. Although heavier than perlite, it can take a while for them to be fully saturated. You also need to rinse them before use as there will be a lot of sediment that falls from them, and this can flow back to your tank and clog your water pumps.

Rockwool

This growing medium has been around for around two decades. They make these by melting rock, where they then spin it into thin fibers. These are then collected together and compressed into bricks of varying sizes. These are great for absorbing water, nutrients and air.

This is another material that is pH neutral, and free from any pathogens. It is ideal for re-use after cleaning/ sterilization, and can last for many years before it is no longer suitable.

The biggest problem with this material being it is the same as household insulation. Because of this, you do need to take caution on first use. Microscopic fibers and dust will escape on first use, and can lead to itching or allergic reactions.

Rockwool needs thoroughly washing to get rid of the threats before use, and while doing so, it is safer to wear rubber gloves and a facemask.

How Hydroponic Nutrients Work

One of the hardest things for new growers to understand is the nutrients used in hydroponics. Many opt for a one-pack solution that they use at all stages of a plants growth. However, these don’t deliver the optimum amounts of specific nutrients to get the best from plants.

Knowing how the nutrients work, goes a long way toward growers making the correct choice of nutrients. Additionally, many problems can be resolved when a grower knows the effects the nutrients have on their crops.

First is, nutrients are classed into two based on the relative concentrations in plant tissue.

Macronutrients

These work on cellular levels, and you find them in larger amounts within plants. The primary focus is to aid photosynthesis, where plants use light to process the food from carbon dioxide and water. They take the chlorophyll (green leaf pigment) and convert carbon dioxide into oxygen.

Essential macronutrients are:

  • Nitrogen
  • Phosphorus
  • Potassium
  • Calcium
  • Magnesium, And Sulfur.

Nitrogen

Nitrogen regulates plant growth and is the most crucial nutrient of all. Plants absorb, digest and convert them into amino acids. These are the core building blocks of proteins. Nitrogen is also one of the core components of chlorophyll.

Phosphorus

Phosphorus is essential for flowering and root growth and is a primary component of DNA and RNA.

Potassium

While you don’t find potassium in any parts of the plant, it does activate plant functions, so it is essential for overall plant health.

Calcium

Calcium works in the same way as it does in humans. If there is a deficiency, it shows signs of stunted or distorted growth, and weakness. Calcium forms into calcium pectate, which is a pectin fiber, and the function in plants is to hold cell walls together, thus giving correct growth and strength.

Magnesium

Plants require chlorophyll so they can photosynthesize. The core property of magnesium is it is the primary structural molecule in chlorophyll production.

Sulfur

Plants need only small amounts of sulfur, but this doesn’t make it any less crucial to their health. The metabolic process in plants break down the sulfur into usable forms such as vitamins and others.

Other compounds sulfur produces are the ones, which produce the smells in garlic and onions (odoriferous).

Micronutrients

There are seven micronutrients, and while these are required in much smaller quantities, they are as essential as macronutrients. The functions of these are to act as activators for further chemical reactions.

  • Iron
  • Manganese
  • Copper
  • Molybdenum
  • Zinc
  • Nickel
  • Boron, And Chlorine

Boron

The function of boron is to aid sugar transportation, amino acid synthesis and cell division.

Chlorine

The purpose of this micronutrient is to aid photosynthesis, help resist disease and for forming rigidity in the plants tissues and cells.

Copper

Copper is one of the key micronutrients that aids photosynthesis through enzyme production.

Iron

Iron is also an enzyme component that is vital for synthesizing chlorophyll and thus aiding in photosynthesis.

Manganese

This is a chief activator for enzymes and chloroplast production.

Molybdenum

Nitrogen metabolism occurs because of molybdenum. It is also a stabilizer of nitrogen some specific plant types (legumes).

Zinc

Zinc is a chief component in many enzymes. It is crucial for the hormone balance in plants and the elongation of cells to regulate plant growth (auxin activity).

How Fertilizers Work

When growers gain more knowledge, they will understand how these nutrients work in their plants growth. There are several fertilizers and nutrient types you can purchase. This is why it is important to know about all the above compounds, especially the macronutrients.

You can purchase conventional fertilizers, or choose to go organic. There are a couple of key differences between these two.

Conventional Fertilizers

These are what you will find readymade, they comprise differing ratios of synthetic or manmade materials. The nutrients in these organic fertilizers are ready for absorption by plants, and deficiencies can be quickly resolved. They are inexpensive and readily available.

Organic Fertilizers

Organic fertilizers are made from broken down (natural) ingredients. These are generally byproducts from waste. The downsides of these is they are more expensive to purchase, and when applied to plants, the nutrients are available at a slower rate.

Liquid vs. Dry Fertilizers

Once you move on from this, you then have liquid vs. dry fertilizer. These can deliver the same results, but the conventional fertilizers in liquid form are much easier to use for newer growers. The downsides being higher cost and shorter shelf life.

Dry fertilizers do take some skill, as they require mixing in the correct ratios. You can tailor these to your plants effectively, and they do come with a lower purchase/ shipping price because they contain no water.

Multi-part or 1-part

New growers will more often go for liquid nutrients. These are available in 1-part or multi-part.

1-part contains all the nutrients needed for plant growth. The most significant downside to this being plants need different levels of nutrients at either stage of their growth. 1-part nutrients can’t be adapted, and you may lose some growth or yield as a result.

Multi-part nutrients come in two or three parts. Each of these caters for a different phase of plant growth. You start with the first part, and once your plants reach a specific point, you then change to the next bottle. If you have a three-part solution, the flowering phase will use the third bottle from your purchase.

It doesn’t matter which route you go, the crucial thing is to ensure plants receive the correct nutrients in the correct ratios. Each type of fertilizer or nutrient has their own benefits, but a crop of plants will not care which one you are using as long as they get their quota.

How Does Water Work in Hydroponic Systems?

Because hydroponics is based around water, this is the primary part of any system. You do need a means to grow your plants, and you will need nutrients, but without water, then nothing can happen.

What many growers don’t know in the beginning, is how water affects a system aside from being the carrier for nutrients and oxygen. Not all water is suitable straight off. You can have water from the faucet, and this will deliver very different results than pure water.

The reason being, faucet water changes depending on region, and, not only this, but it is not pure because of chemical treatments. This affects your water, and ultimately, it has an effect on your plants.

Reverse osmosis, or clean rainwater is ideal for a hydroponic system. These have no trace elements that can affect mineral or pH levels in your solutions.

There are a few things to understand how water works because it changes once you begin adding your nutrients, and when your plants begin absorbing these nutrients along with water.

How EC (Electrical Conductivity) Works

When you have pure water, it isn’t an efficient conductor of electricity. Once you add your nutrients (mineral salts), the EC levels rise. This means electricity can pass through the solution easier. The higher the salt concentration, the higher your EC.

With this, you can tell how strong your nutrient solution is. When growing, this will rise naturally because plants absorb water faster than they take up nutrients. It is here, you need to know how water works with EC.

Once your EC levels reach a certain point, it will affect the growth of your plants. If it is too low (less nutrient concentration), your plants may not receive all they need. If you have a reading which is too high (strong nutrient concentration), then your plants will be showing symptoms that are affecting their growth.

There is an optimum EC level for each type of plant. Regular testing with a digital EC meter is advisable.

Even though plants may suffer slightly from weaker concentrations, it is better to edge toward weaker rather than stronger. It is easier to adjust, the damage to plants is less, and easier to rectify.

How pH Works in Hydroponic Systems

The pH levels in your system are one of the key factors in your water working effectively. This is the measure of acid or alkaline in your system.

Along with your EC levels, the pH level will change when you add your nutrients. The key factor here is it will affect how easily your plants can absorb the nutrients from the water. It is these fluctuations in either direction, which causes nutrient lockout.

Once this happens, the key macronutrients are harder to absorb, yet the micronutrients become easier and in larger quantities, these become toxic to plants.

You can purchase a simple digital pH meter, which works in the same way as your EC meter. The ideal pH levels for plants is in between 5.5 and 6.5. It may be the case; you need to measure solutions daily until you understand how your system works.

Conclusion

Hydroponics works in many ways because there are countless variables at play. For many new growers, it can be hard to understand each part and how they go to affect the performance of a system. One thing to remember is it was possible for growers thousands of years ago to do the same thing using sand and gravel. Although it can be frustrating at times. There is no part of a hydroponic system, which causes problems; a grower can’t find a solution for. This leads them to a fruitful and successful system they are in complete control of.

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About the Author

Oscar Stephens
Oscar Stephens
I am a gardening and tech enthusiast! Stumbling across the world of Hydroponics, Aquaponics and Aeroponics by accident I've decided to create TheHydroponicsPlanet to put all of the best information I can find in one easy to navigate place. I'll continue to add more content as I discover new things!